It's hard to hear people behind you in this game, 99% of the time I got stabbed I couldn't hear Jack.

That is the truth, but it makes knifing so much more fun. It's easy to run up behind 3 snipers and take them all out. You just couldn't do it in BC2 because of the shout you did. The others would almost always turn around.

I was never a fan of Hardcore mode in CoD, and no in BF3 tbh.
Auto snipers are very powerful, the last sniper rifle is a guaranteed one shot kill as well, only time u play HC is maybe if you want to unlock stuff quicker for sniper class